Expiring Today—Celebrate National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Control Name From Text

Posted on 2011-09-14
7
Medium Priority
?
274 Views
Last Modified: 2012-05-12
Is it possible to access a control using a text value?  That is, can I do something like this:
For i As Integer = 1 To 5
    Dim sText = "btnAdd" & i.ToString()
    sText.Enabled = False  '<-- Yes, I know this specific line is wrong.  What is right?
Next

Open in new window


Hopefully you understand what I'm trying to do, and can help.
0
Comment
Question by:Clif
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
  • 2
  • +1
7 Comments
 
LVL 6

Expert Comment

by:yjchong514
ID: 36536967
R u mean assign text value to button object??
0
 
LVL 40

Accepted Solution

by:
Jacques Bourgeois (James Burger) earned 1000 total points
ID: 36536978
Call it through the Controls collection in the form:

Me.Controls(sText).Enabled = False

Open in new window


If you are calling a property that is common to all controls, that will be enough. If however you want to call a method or property that is specific to a Control, you will have to tell the compiler which control it is through a DirectCast:

DirectCast(Me.Controls(sText),TextBox).MaxLength = 7

Open in new window

0
 
LVL 10

Author Comment

by:Clif
ID: 36537268
It's not working, though I don't know why.

The error thrown is:
Object reference not set to an instance of an object.

I check the spelling, etc, and it's all correct.

The only thing that's different in the actualk app is the fact that I'm running the code in a subroutine in a module (where the form is passed to the subroutine), like this:
Public Sub disableContols(ByVal frmSource As frmMain)
    For i As Integer = 0 To frmSource.NumButtons '(NumButtons is a readonly property of frmSource/frmMain)
        Dim sButtonName As String = "picSiteImage" & i.ToString("00")
        DirectCast(frmSource.Controls(sButtonName), Button).Enabled = False
    Next
End Sub

Open in new window

0
What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

 
LVL 86

Assisted Solution

by:Mike Tomlinson
Mike Tomlinson earned 1000 total points
ID: 36537340
The error is caused because the control is not being found.  

Instead of using Controls(someString), use Controls.Find():
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.controlcollection.find(VS.80).aspx
*Or use the Controls collection of the particular container directly, as in Panel1.Controls(someString)

Public Sub disableContols(ByVal frmSource As frmMain)
    Dim ctls() As Control
    For i As Integer = 0 To frmSource.NumButtons '(NumButtons is a readonly property of frmSource/frmMain)
        ctls = frmSource.Controls.Find("picSiteImage" & i.ToString("00"), True)
        If ctls.Length > 0 AndAlso TypeOf ctls(0) Is Button Then
            DirectCast(ctls(0), Button).Enabled = False
        End If
    Next
End Sub

Open in new window

0
 
LVL 40
ID: 36537543
Idle_Mind has a point. if the Button is included in a container, you wont't get it by looping through the form controls. You will need to loop through the container controls.

Which of the lines trigger the error?

Check the value of all the variables on that line. If one is Nothing, then it is the culprit.

It could be the control, but it could also be frmSource.

You could also temporarily try the following to make sure that the name you are looking for exists in the collection:
Public Sub disableContols(ByVal frmSource As frmMain)
    For i As Integer = 0 To frmSource.NumButtons '(NumButtons is a readonly property of frmSource/frmMain)
        'Dim sButtonName As String = "picSiteImage" & i.ToString("00")
        'DirectCast(frmSource.Controls(sButtonName), Button).Enabled = False
        Debug.WriteLine(frmSource.Controls(i).Name)
    Next
End Sub

Open in new window

The name of all the controls that your loop see will be displayed in the Output window.
0
 
LVL 10

Author Closing Comment

by:Clif
ID: 36537763
The find was the key.

The control was within a container within a container.  Too much hassle to find it without "Find"

Thanks.
0
 
LVL 86

Expert Comment

by:Mike Tomlinson
ID: 36537778
*If they are all in the same container then use that containers name:

    Panel2.Controls("blah")

If they are in multiple containers, or you need the code generic for future changes, then use Find().
0

Featured Post

Important Lessons on Recovering from Petya

In their most recent webinar, Skyport Systems explores ways to isolate and protect critical databases to keep the core of your company safe from harm.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This tutorial demonstrates one way to create an application that runs without any Forms but still has a GUI presence via an Icon in the System Tray. The magic lies in Inheriting from the ApplicationContext Class and passing that to Application.Ru…
The ECB site provides FX rates for major currencies since its inception in 1999 in the form of an XML feed. The files have the following format (reducted for brevity) (CODE) There are three files available HERE (http://www.ecb.europa.eu/stats/exch…
Visualize your data even better in Access queries. Given a date and a value, this lesson shows how to compare that value with the previous value, calculate the difference, and display a circle if the value is the same, an up triangle if it increased…
In this video, Percona Solution Engineer Rick Golba discuss how (and why) you implement high availability in a database environment. To discuss how Percona Consulting can help with your design and architecture needs for your database and infrastr…

730 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question